Research On Bank Slope Rock Stability Of Najie River Bridge In Lin-Zhi Railway

With our nation support for railway construction in Southwest region, GuiZhou in response to the national call, planning and constructed of a lot of far-reaching railway lines. Lin-Zhi railway as an important line in GuiZhou railway network, the successful construction and operation has fatal significance for Guizhou’s economic and industrial structure.Lin-Zhi railway as long as 99.559km, pass through multiple tectonic units, affected by the active fault zone and the geological conditions, bridgs and tunnels are very common forms, The Najie River Bridge has steep slopes, complex lithology, rocks cutting by multiple joints, it is the most difficult part in line. To finish the Najie river bridge has important meaning for the whole line.The purpose of this paper is as follows:to evaluate the stability of structure surfaces in slope rock mass Najie river bridge; to use the empirical formula to determine the stable slope toe of bank slope; to determine the failure mode of rock slope by distinct element method; to determine the slope stability by finite element method.The main contents of this paper and the results are as follows:(1) Through the investigation of geological conditions on both sides of the slope in site, to have a full understanding of the site geological conditions, to measured multiple occurrences, opening width and joint spacing of the control factors of rock mass quality.(2) To obtain the strength of structural surface by the Barton model, by using stereographic projection method to analyze the single or wedge surface stability of both sides. The collapse will be the main form of scattered on both sides of the slope failure results.(3) Through the empirical formula to seek out the natural stable slope on the left bank of river bridge is 65°, on the right bank is 59°, have certain reference significance for the stability of slope under load.(4) Through the analysis of the results show by the distinct element method, the rock mass movement is still in development stage in natural condition, there may be local collapse on rock masses on slope, the most dangerous part is rock slope changing points. Overall, the load has little effect on rock masses around the bridge pier, but it is unfavorable on the base rock stability.(5) The calculation results of finite element analysis show the left bank, right bank slope on both sides of the basic stability along the line profile. The safety factor under natural conditions were 1.60,1.90, the safety coefficient under load are respectively 1.30, 1.40.(6) Because of the weathering of rock cliff on the left bank is strong, Joint fissure are development, and have found the collapse rocks, recommended to anchor the weathered rock. On both sides of slope bottom are developed fissures and bedding, recommended to manage the bottom joint by shotcrete reinforcement. Both sides of Najie river slope are limestones and dolomitic limestones, because the bottom near the river, to dissolute and form formation of voids and free surface, recommended to use karst grouting、surface drainage of the slope and other treatment measures.